Electrical discharge device



Nov. 1, 1932. F. sLM cuLLouqH 1,885,125

ELECTRICAL DISCHARGE DEVICE Filed April 1929 [4/5 A 7'7OP/VEK l atent ed Nov. 1 19 32 h r Y 7 I UNITED STATES PATENT"O I E- FREDERICK s. MCCULLOUGI-I, or snenwoon 3030mm, PENNSYLVANIA ELECTRICAL DISCHARGE DEVICE,

Application filed April 8, 1929. Sam 110. 9.533.96.

My invention relates to devices operating main ata relatively'low temperatureand to by electrical discharge, such as triodes and give little trouble even without resort 'to' electronic rectifiers, and particularly to such specialprecautions. "As regards amplifying devices handling large power, its broad purtriodes, where the grid is operatediwi'th a 5 pose being to increase the rating at which strong negative biasfat' all times, this is in 55 such apparatus may safely be operated. generalltrue. "Where a triode is used asan An object of my invention is to prevent oscillator, however,'the grid swings positive cracking of the seals of electrical discharge during a portion of the cycle, and during this devices, owing to differential thermal experiod notonly the grid but also its support;

pansion. and the glass of the seal itself are subjectto 60 Another object of my invention is to preelectronic bombardment. This entails an vent the liberation of adsorbed gases from evolutionof heat with the attendant troubles the seals of such devices, either by the action already set forth, and in large triodes: the of heat conducted to the seals or by accidental grid support and its seal may befthe hot 7 electronic or ionic bombardment. spotbwhich sets the limit to poweroutput. 65

My invention possesses other objects and My invention servestoincrease the power. valuable features, some of which will be set limit thus'set. i forth in the following description of my in- Referring to the drawing, the single figure vention which is illustrated in the drawing is an axial longitudinal section of the device forming part of the specification. It is to of my invention asfen'ibodie'd in a power. 70'' be understood that I do not limit myself to triode. v j l j j f the showing made by the said description Broadly stated,- my invention comprises, and drawing, as I may adopt varying forms a shield positioned to intercept electrical of my invention within the scope of the bombardment ofthe envelop, and particuclaim. larly of the seal of an electrical discharge 75 The capacity of electronic apparatus, like device. The shield is preferably carried, on that of most electrical devices, is limited by the support for one of the electrodes of thethe heat evolved in the apparatus when under device, and this support is 1 provided with a load. The effect of this evolution of heat, devious passage forconductin'g 'a cooling with its consequent temperature rise, may be fiuidj The electrode may therefore be opso manifested in different ways. The electrodes erated at a relatively high temperature withthemselves may be destroyed, the envelop may out endangering the seal. v be melted, the seals may crack, or the vacuum Describing in detail [one embodiment of may be so lowered by the liberation of admy invention, a substantially cylindrical sorbed gases as to render the device inopervitreous envelop 6 encloses a water-cooled s5 ative. anode '7 and a filamentary cathode 8, ar-

The advent of water-cooled anodes has ranged as described in my co-pending appligreatly increased the possible maximum v cation, Serial No. 286,370, filed June 18,1928. power for which such apparatus may be con- Projecting through the end of the envelop structed, and where they are used they pracis a tubular support member 9, whose inner f tically eliminate the first two causes of fail end is provided with a closure 11. An anure. This makes the seals the most 'vulnernular groove 12 encircles the support, and is able part of the device, for beside being sub bridged by a thin metal sleeve 13, welded at ject to failure by cracking, they are the areas one end to the support, to which sleeve the I 45 where adsorption of gas is most likely to 00- envelop is joined by the seal 14: as is deour, and the most dilficult to free of gas which scribed in my co-pending application," Sehas been adsorbed. rial No. 269,439, filed April 12, 1928.

Owing to the small absorption of power Fixed at the end of the support 9, and in in the grid circuit of a triode, the grid supclose thermal contact therewith, is a 'diskport and its seal might be expected to reshaped shield 16, so positioned as to interloo prising an envelope, an anode Within the en cept electronic bombardment directed to the seal from the electrodes or the inter-electrode space. The grid 17 Which is preferably of an easily degasified material such as molybdenum, is carried by Wires 18 which are fixed to the shield.

A devious passage, in this embodiment a folded passage, is provided within the sup port for" conducting a cooling medium, which may be any suitable fluid such as Water, oil

or air. phi-g la, moun ed: on he o t r nd:

of the support, carries a tube 21 which extends thru the plug and concentrically Within the support nearly to the closed inner end. An upset 22 is provided at the outer end of the-tube, to. tacilitate a hose connection, and a similarly upset hose nipple. 23 extends laterally h iu. the ide of e pport Either t he morsyphon or pressure methods may be usedtocirculatethe cooling fluid.

It willbe seen thatthis arrangement provides almost perfect protection for the seal. 'ljhe, close thermal Contact between the shieldthe cooled Support permits a, rapid transfer of heat thushlgeeping the shield itself cool and preventing the heating of the seal by radiation from the shield. Conduction of heat from the grid is not so rapid, but since it cannot heat the shield by radiation it may be permitted; to operate at a relative,- ly high temperature, and the cooled support prevents the' transfer of this temperatureto rec a ms devilce ofthe character described, comvel ope, a cathode Within the envelope, a post Passing l l gh he env lope having a filild, circulat ng passage therein, a sh eld C rried y th Pe W thin the env op a g idle trode W t in. the enve p Carried and supported on the shield, the shield being ofi a diameter greater than the diameter of the grid and approximately spanning the distance between the anode and cathode but in pac d relation. o he a d d. ca e- In testimony whereof, I have hereuntoset FR D RICK M LL UG 

